The Impact Of Genetic Mutations In 5α-Reductase Enzyme And INSL3 Hormone On The Development Of Hypospadi-as And Cryptorchidism

Abstract

Congenital malformations of the genitourinary system, such as hypospadias and cryptorchidism, are among the most researched conditions to understand their molecular causes. This study aims to shed light on the role of genetic mutations in the SRD5A2 and INSL3 genes and their impact on the occurrence of these malformations. Cryptorchidism is a condition in which one or both testicles fail to descend into the scrotum. is associated with an increased risk of infertility and testicular germ cell tumors. Testicular descent is a complex process, often described in two separate stages: the transabdominal stage and the inguinal-scrotal stage. In the first stage, which occurs between the 10th and 15th weeks of pregnancy, the testicle migrates from the abdominal area to the area near the deep inguinal ring. The main hormone that drives this stage is insulin-like peptide 3 (INSL3), produced by Leydig cells. Insulin-like peptide 3 (INSL3) is a small peptide hormone of the insulin-relaxin family. It is produced and secreted by embryonic Leydig cells in the testes only and is undetectable in female fetuses. INSL3 synthesis begins in the human fetus immediately after gonadal sex determination, at 7 to 8 weeks after fertilization. This peptide can be detected in the amniotic fluid 1 to 2 weeks later. A mutation in the INSL3 gene causes a defect in the efficiency of producing the INSL3 hormone that this gene encodes, which leads to a defect in the descent of one or both testicles into the scrotum. This is what was identified by the genetic variation found in all samples of patients with cryptorchidism.After the ninth week, under the influence of testosterone, the genital tubercle and urinary folds (penis) are formed, while the labial folds (scrotum) are formed. This process is stimulated by androgen hormones, The conversion of testosterone to dihydrotestosterone is catalyzed by the steroid 5α-reductase type 2 enzyme, which plays a crucial role in the masculinization of the external genitalia. It is encoded by the SRD5A2 gene. Allelic variants in this gene cause XY 46 chromosomal abnormalities. The occurrence of the V89L polymorphism and the G34R mutation in the gene responsible for encoding this enzyme reduces the efficiency of production of this enzyme, causing a decrease in testosterone and dihydrotestosterone levels and causing a defect in the formation of the urethra.The study included a group of children diagnosed with hypospadias or cryptorchidism. DNA samples were analyzed to detect the V89L and G34R mutations in the SRD5A2 gene, in addition to examining changes in the INSL3 gene using RFLP (PCR),Allele-specific (PCR)and DNA sequencing techniques. The results showed that the studied mutations in the SRD5A2 gene lead to impaired function of the enzyme 5α-reductase type 2, resulting in a deficiency in the production of dihydrotestosterone, which is essential for the normal development of the male reproductive organs. Mutations in the INSL3 gene also contributed to impaired testicular descent into the scrotum, leading to an increase in the incidence of cryptorchidism.  These findings highlight the importance of early genetic testing for children with congenital reproductive abnormalities, which could contribute to improved diagnosis and early therapeutic intervention, as well as providing accurate genetic counseling to families. The study showed that 14 of the 15 children with hypospadias carried the V89L mutation in the SRD5A2 gene, while one child carried the G34R mutation. A new, previously undocumented recurrent mutation was also discovered in 15 other children with cryptorchidism.